On Mon, Nov 11, 2019 at 6:01 PM Edward Cree <ecree@xxxxxxxxxxxxxx> wrote: > > On 11/11/2019 17:38, Arthur Fabre wrote: > > On Mon, Nov 11, 2019 at 5:27 PM Edward Cree <ecree@xxxxxxxxxxxxxx> wrote: > >> > >> On 11/11/2019 10:51, Arthur Fabre wrote: > >>> diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c > >>> index a7d9841105d8..5bfe1f6112a1 100644 > >>> --- a/drivers/net/ethernet/sfc/rx.c > >>> +++ b/drivers/net/ethernet/sfc/rx.c > >>> @@ -678,6 +678,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel, > >>> "XDP is not possible with multiple receive fragments (%d)\n", > >>> channel->rx_pkt_n_frags); > >>> channel->n_rx_xdp_bad_drops++; > >>> + trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act); > >>> return false; > >>> } > >> AIUI trace_xdp_exception() is improper here as we have not run > >> the XDP program (and xdp_act is thus uninitialised). > >> > >> The other three, below, appear to be correct. > >> -Ed > >> > > > > Good point. Do you know under what conditions we'd end up with > > "fragmented" packets? As far as I can tell this isn't IP > > fragmentation? > > Fragments in this case means that the packet data are spread across > multiple RX buffers (~= memory pages). This should only happen if > the RX packet is too big to fit in a single buffer, and when > enabling XDP we ensure that the MTU is small enough to prevent > that. So in theory this can't happen if the NIC is functioning > correctly. > > -Ed Makes sense, thank you for the explanation.
